Ignition magneto



Patented Nov. 8, 1932 UNITED STATES PATENT OFFICE GIUSEPPE FOSSATI, OFMONZA, ITALY, ASSIGNOR TO FABBRICA ITALIANA MAGNETI MABELLI SOCIETAANONIMA, 0F MILAN, ITALY, A CORPORATION OF ITALY IGNITION MAGNETOApplication filed July 30, 1930, Serial No.

The present invention has for its object a method for providing shoesfor the inductor field in ignition maghetoes.

This invention includes a method for connecting inductive permanentmagnets with the field structure, and also concerns the inductor unitobtained by said methods.

In accordance with this invention the field shoes consist of a block orpile of superimposed iron sheets which are interconnected by means ofrivets and by temporary connecting means, the said pile being located ina die in which the metal body or frame of the magneto is cast.

At the time of casting, the said field parts are thus embedded andpositioned within the metal providing the said body or frame, andthereafter said temporary connecting means are removed through aperturesof the magneto body or by machining.

Further in this invention the iron sheets providingthe said pilecomprise an interme diate portion which is identical for all the ironsheets, and on their sides these sheets have extensions which areofl'set in each pair of superimposed iron sheets.

Thus to the faces of the inductor field shoes opposite the magneto rotora sufficient area for the flow of the total magnetic flux is impartedwhile their extensions engaging the permanent inductor magnets have athickness which is reduced to the minimum permissible value. I

Further in this invention inductor permanent magnets are used which arebar-shaped and have tapering heads which are shrunk in apertures of thesaid inductor parts.

On the annexed drawing is shown by way of example an embodiment of thepresent invention and i Figure 1 is a transverse section on line 1-1 ofFig. 5 of a magneto having an inductor unit according to this invention;

Figure 2 shows two superimposed sheets of the inductor in theirrespective superimposed position;

Figure 3 shows the sheet pile as assembled for location in a die forcasting the magneto body in which it is to be embedded;

471,821, and in Italy September 5, 1929.

To provide the pile, the subsequent sheets are located With theirintermediate regions 11' superimposed and coincident with each other,while their extensions 23, 23 are offset from each other, each sheetthus leaving a free space in register with the extension 2-3 of theunderlying and overlying sheets.

The several sheets 1, 1' are arranged in a pile and are interconnectedby means of rivets 4; then their extensions are bent into the requiredshape as shown in Figure 3, and they are held in such shape by means ofscrew-threaded rods 5 having end nuts 6 and intermediate spacing sleeves7.

A further transverse laminated pile 8 assembled by means of rivets 9 andstrips 10 of non-magnetic material is fastened on pile 1, 1 by means ofside lugs 8 engaged by rivets 11 fastened on a plate 12.

The unit shown in Fig. 3 is located in a die in which the magneto bodyis to be cast, it being thus embedded in the metal mass of magneto body18 (Fig. 1), which is formed, as usual, of aluminum.

After casting, the interconnecting rods 5 are removed, suitable boresbeing provided therefor in casting and the bores 15 of the magneto bodyand of the extensions 2, 3 are machined to their correct size, thesleeves 7 1 being thus destroyed. Then a bar shaped magnet 13 havingtapering heads 13 is inserted in each pair of aligned bores 15 and isdriven or pressure-forced therein, said .magnet being thus permanentlyengaged within the magneto body with its heads in intimate connectionwith arms 2, 2 and 3, 3 embedded in said body and passed through by saidbores 15 for providing a satisfactory flow of magnetic flux through saidmagnet and pole members 2, 2, 3, 3.

Then the bore 17 for the rotor 14 is machined and thus the portions ofthe unit enclosed within the dotted circle in Fig. 8 are removed, theconstruction shown in Figure 1 being obtained. 4

As above stated each magnet includes an intermediate bar shaped portion13 and two end heads 13--13 having tapering shape and adapted to beshrunk within the bores 15 of the inductorunit. 7

Of course, the magnets 13 may have any desired profile or cross section,and they may be cylindrical or prismatical, it being essential only thatthey have tapering heads all drawn on a single line, that is lying onthe same conical or'tapering surface.

Thus a good contact of the magnets with the field is secured withoutrequiring screws or screwthreaded portions which are liable to becomeloose due to jolts and vibrations.

What I claim as my invention and desire to secure by United StatesLetters Patent 1s 1. A method for providing pole shoes in the fieldstructure for ignition magnetoes, consisting in providing a pile ofsuperimposed sheets of magnetic metal, connecting them by connectingmembers, locating said pile in a die and casting therein the magnetobody, and after casting removing the excess of said pile and said'connecting members.

2. A method for providing pole shoes in the field structure for ignitionmagnetoes, consisting in providing a pile of superim posed sheets ofmagnetic metal, connecting them by connecting members, locating saidpile in a die and casting therein the magneto body, said pile extendingacross the body portion where a rotor seat is to be provided,

and after casting removing the excess of said pile and said connectingmembers.

3. A method for providing pole shoes in the field structure for ignitionmagnetoes, consisting in providing a pile of superimposed sheets ofmagnetic metal each of said sheets including an intermediate portioncoincident in all said sheets and extensions projecting from saidintermediate portion and ofiset in superimposed pile sheets, connectingthem by connecting members, locating said pile in a die and castingtherein the magneto body, and after casting removing the excess of saidpile and said connecting members.

4. A method for providing pole shoes in 1 the field structure forignition magnetoes,

consisting in providing a main pile of superimposed sheets of magneticmetal, connecting them by connecting members, fastening a second pile ofmagnetic metal sheets on said main pile, locating the assembled piles ina die and casting therein the magneto body, and after casting removingthe excess of said piles and their connecting members.

5. A method for providing pole shoes in the field structure for ignitionmagnetoes,

consisting in providing a main pile of superimposed sheets of magneticmetal, each of said sheets including an intermediate portion coincidentin all said sheets and extensions projecting from said intermediateportion and offset in superimposed pile sheets, connecting them byconnecting members, fastening a second pile of magnetic metal sheets onsaid main pile, locating the assembled piles in a die and castingtherein the magneto body, and after casting removing the excess of saidpiles and their connecting members.

6. A method for providing pole shoes in the field structure for ignitionmagnetoes, consisting in providing a pile of superimposed sheets ofmagnetic metal, connecting them by connecting members, bending said apile to provide facing portions, locating said pile in a die and castingtherein the magneto body, after casting removing the excess of said pileand said connecting members, providing aligned tapering holes in saidfacing portions and forcing a tapering-headed barshaped permanent magnetin each pair of said aligned holes.

7. A method for providing pole shoes in the field structure for ignitionmagnetoes, consisting in. providing a pile of superimposed sheets ofmagnetic metal, each of said sheets including an intermediate portioncoincident in all said sheets and extensions projecting from saidintermediate portion and offset in superimposed pilesheets, connectinthem by connecting members, bending sai pile to provide facing portions,locating said pile in a die and casting therein the magneto body, aftercasting removing the excess of said pile and said connecting members,providing aligned tapering holes in said facing portions and forcing atapering-headed barshaped permanent magnet in each pair of said alignedholes.

8. A method for providing pole shoes in the field structure for ignitionmagnetoes, consisting in providing a main pile of superimposed sheets ofmagnetic metal, connecting them by connecting members, bending said pileto provide facing portions, fastening a second pile of magnetic metalsheets on said main pile, locating the assembled piles in a die andcasting therein the magneto body, after casting removing the excess ofsaid piles and their connecting members, providing aligned taperingholes in said facing portions and forcing a tapering-headed barshapedpermanent magnet in each pair of said aligned holes.

9. In a magneto, an inductor unit comprising laminated blocks embeddedin the magneto body, each of said blocks providing a pole face in themagneto rotor seat and having an extension, the extensions of saidblocks being opposite to each other and provided with aligned taperingholes, and tapering-headed bar-shaped magnets each with its taperingheads engaged in a pair of said being opposite to each other, andbar-shaped aligned tapering holes. magnets each having its endsconnected with 10. In a magneto, an inductor unit com said oppositeextensions. prising laminated blocks embedded in the In testimonywhereof I have signed my magneto body each of said blocks providing nameto this specifiction. 3 a pole face in the magneto rotor seat andGIUSEPPE FOSSATI. having an extension, the extensions of said blocksbeing opposite to each other and provided with aligned tapering holes,aligned laminated blocks located intermediate said first name blocks andproviding pole faces in said rotor seats, and tapering-headed barshapedmagnets each with its tapering heads engaged in a pair of said alignedtapering holes.

11. In a magneto, an inductor unit comprising blocks embedded in themagneto body each of said blocks providing a pole face in the magnetorotor seat and an extension and consisting of superimposed and coinci-3a dent sheets in register with said pole face and of staggered sheetsin said extension, said extensions of said blocks being opposite to eachother in pairs and having aligned tapering holes, and tapering-headedbar- 83 shaped magnets each with its tapering heads engaged in saidaligned tapering holes of said opposite extensions.

12. In a magneto, an inductor unit comprising blocks embedded in themagneto body as each of said blocks providing a pole face in the magnetorotor seat and an extension and consisting of superimposed andcoincident sheets in register with said pole face and of staggeredsheets in said extension, said ex- 100 tensions of said blocks beingopposite to each other in pairs and having aligned tapering holes,tapering-headed bar-shaped magnets each with its tapering heads engaged.in said aligned tapering holes of said opposite ex- 105 tensions, andaligned laminated blocks embedded in said magneto body intermediate saidfirst named blocks and providing pole faces in said rotor seat. 13. In amagneto, an inductor unit com- 110 prising two blocks each formed of astack of superimposed sheets of magnetic metal and embedded in themagneto body, each of said blocks comprising a main section whichprovides a pole face in the magneto rotor 11b seat and an extension ofreduced thickness with respect to said main section, said extensions ofsaid two blocks being opposite to each other, and bar-shaped magnetseach having its ends connected with said opposite extensions.

14. In a magneto, an inductor unit comprising two blocks each formed ofa stack of superimposed sheets of magnetic metal and embedded in themagneto body, each of said blocks comprising a main section V whichprovides a pole face in the magneto rotor seat and an extensioncomprising only a portion of said sheets existing in said main Qsection, said extensions of said two blocks

